The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In the state of the art, drilling robots which allow in particular to realize drilling series using drills, are already programmed. The drilling tool is mounted at the end of an articulated arm, for example with six degrees of freedom. Each axis is equipped with an actuator which allows to move the end of the arm in a determined position and orientation. The result is that the drilling tool can be approached according to a determined orientation in each programmed position of a sequence of drillings executed according to a determined program.
Thus, in response to the drilling program which is registered and executed on the controlling device of the driller robot, the drilling tool secured to the end of the robot arm undergoes a positive acceleration, then a negative acceleration (braking) during the approach of the following drilling position. When the drilling tool is finally stopped, an unsteady state may be established, the tool starting to oscillate around the reached drilling position. This instability depends on various factors comprising the approach acceleration, the inertia of the robot arm and others.
If the drilling was controlled upon detection of the end stop, the drilling would be entirely defective, with a non-cylindrical form and an ovalized section.
To overcome this drawback, it is known to count an inhibition period of the drilling to be counted from the stop detection on a drilling position so as to guarantee that the inertias and other braking forces of the unstable oscillations have absorbed the instability. The longest natural stabilization period provided in all programmed movements is chosen to realize the drilling program.
In an exemplary form, the drilling inhibition period was established at 2.5 sec.
But it was found that for all programmed positions, if no stabilization period is not longer by definition, an important number of stabilization periods were shorter than the retained inhibition duration. There is therefore a waste of time during the execution of the drilling program.
Furthermore, it was found that, during the drilling execution, because of many parameters, comprising the material irregularity of the part to be drilled, balancing or wear defects of the perforating drill and others, an unsteady state could still appear on the drilling tool. Among the drawbacks of these instabilities, the ovalization and the delamination problem(s) can be cited.